This invention relates to combination locks, and, more particularly, to combination locks constructed to virtually eliminate unwanted changes to the pre-set combination.
Numerous lock constructions have been developed and are widely employed by individuals to prevent unauthorized persons from gaining access to any area which has been closed and locked. Although many locks are constructed to be opened by a key, numerous combination locks have been developed which are opened by knowledge of a particular combination.
One particular type of combination lock that has become very popular due to its ease and convenience of use is a combination lock which employs a plurality of rotatable independent dials, each of which forms one of the indicia, usually numerals or letters, comprising the combination for releasing the lock. Although locks of this general nature have been available for several decades, these prior art combination lock constructions suffer from common deficiencies which have not been successfully overcome.
Although many manufacturers have attempted to solve the problems associated with rotatable dial or combination locks, these prior art constructions have been unable to produce a construction which substantially eliminates the ability of unauthorized persons discovering the combination for opening the lock. Although numerous attempts have been made in prior art constructions for achieving a system which would eliminate or prevent unauthorized opening or picking of a lock, these prior art constructions have failed to provide the desired results.
Another common problem which has consistently plagued prior art constructions is the cost of construction for producing and assembling prior art combination locks. In order to attain a combination lock which provides all of the features desired by consumers, prior art constructions typically incorporate numerous small components, each of which require expensive assembly procedures to produce the final product. As a result, these prior art lock constructions typically are expensive to produce, thereby reducing the ability of these locks to reach a broad base of consumers.
Another problem commonly found with prior art combination locks is the inability of these prior art constructions to prevent contaminants from reaching the rotatable, internal components of the lock, thereby causing damage to these components or interfering with the ease of operating the lock by an individual knowing the actual combination. Although numerous attempts have been made to reduce the adverse effects caused by contaminants reaching these components, such attempts have been incapable of satisfactorily eliminating this problem.
A further problem, which has consistently annoyed the user and caused the user to incur substantial problems is the ability of many prior art combination locks to enter a combination re-setting mode, without the user""s knowledge. As a result, consumers are often unable to open a lock or cannot use the lock since the desired combination had been altered without their knowledge.
Therefore, it is a principal object of the present invention to provide a combination lock construction which virtually eliminates the ability of unauthorized persons from gaining access to the lock by attempting to pick the lock using known techniques.
Another object of the present invention is to provide a combination lock having the characteristic features described above which employs a minimum of components and is quickly and easily assembled, thereby providing a lock capable of being constructed at a competitive price.
Another object of the present invention is to provide a combination lock construction having the characteristic features described above which effectively seals the rotating components from external contamination and effectively prevents any external contaminants from reaching the rotating components thereof.
Another object of the present invention is to provide a combination lock construction having the characteristic features described above which prevents the combination for the lock from being accidentally changed or altered without the user""s complete knowledge.
Other and more specific objects will in part be obvious and will in part appear hereinafter.
By employing the present invention, all of the difficulties and drawbacks of the prior art constructions are virtually eliminated and an effective, easily produced, combination lock is achieved which is capable of virtually eliminating the ability of unauthorized persons from opening the lock, using known picking techniques, while also preventing the combination from being accidentally changed or altered. Furthermore, the lock construction of the present invention is constructed with the interior chambers thereof virtually sealed from ambient surroundings, thereby preventing unwanted contamination from entering the interior of the lock and the rotating components thereof. In this way, the prior art degradation and interference of the lock operation by contamination is virtually eliminated.
In accordance with the present invention, a minimum number of components are employed in combination with a housing and a movable shackle in order to provide the desired, unique combination lock construction of this invention. In general, in addition to the shackle and housing, only a plurality of rotating dials and a plurality of tumbler sleeves are required to provide the desired locking mechanism. Preferably, in order to assure user security that a locked item remains locked and incapable of access by unauthorized personnel, four dials and tumbler sleeves are employed with the housing.
As is well known in the lock industry, individuals seeking to pick or open a lock without knowledge of the combination use the audible sound produced by the tumbler entering the open chamber when properly aligned therewith. By rotating a dial and listening for the sound produced when the proper position is reached, such trained individuals are capable of determining the requisite position for each tumbler, without knowledge of the actual combination.
In the present invention, the ability of unauthorized persons to determine the actual combination using the sound is thwarted by incorporating in the housing a plurality of false void zones having a construction similar to the actual open chamber or open zone which provides the lock release for each tumbler. By providing a plurality of false void zones as part of the lock construction, the ability of trained individuals to pick the lock is virtually eliminated.
In the preferred construction, the central housing of the combination lock of this invention incorporates an elongated lock release groove or slot which provides the lock release zone for each of the independent rotatable tumbler sleeves. In addition, the housing also incorporates a plurality of non-releasing open zones or slots formed in association with the lock release groove for each rotatable tumbler sleeve. In this way, the desired false click is provided for each rotatable dial in order to thwart unwanted opening of the combination lock of this invention.
In addition, in the preferred construction, all of the rotatable components are mounted in a single elongated bore formed in the housing and a sealing cap is employed to effectively close and seal the elongated bore once the components are mounted therein. As a result, ease of assembly is attained and, once assembly is completed, the elongated bore and the rotational components positioned therein are effectively sealed from external contamination. As a result, dirt, dust, debris, etc., commonly present in the environment, is eliminated from contaminating the working components of the combination lock of this invention. In this way, contamination from environmental sources which has often caused prior art lock assemblies to become defective or injured is effectively overcome.
In addition to these features, the present invention achieves a combination lock using a minimum number of independent components each of which is capable of being quickly assembled into the final product. As a result, a construction is attained which is capable of being manufactured at a competitive price, while providing a high quality, highly effective combination lock which prevents exposure to environmental contamination and also incorporates means for virtually eliminating unauthorized persons from opening the lock without knowledge of the combination.
Another important feature incorporated into the lock of the present invention is the control elements which prevent the pre-determined combination from being changed or altered without the user""s knowledge or control. In order to attain this important and highly desirable control, the combination lock of the present invention incorporates a shackle holding assembly comprising a holding member or a sleeve or bowl which is mounted to the free end of the elongated leg of the shackle, with the sleeve/bowl incorporating a radially extending outer rim.
In addition, spring means are mounted in cooperating relationship with the rim of the sleeve/bowl, with the spring means being maintained under compression between the sleeve/bowl and a bottom surface of the housing of the combination lock.
In the preferred construction, a plug member is employed for forming the cooperating contact surface on which the spring means is maintained. In this way, ease of assembly is attained with a minimum of components being employed.
In typical prior art combination lock assemblies, the combination is changed by axially moving the long leg of the shackle downwardly towards the base or bottom of the lock housing in order to release the tumblers and allow the indicia bearing dials to freely rotate. However, in these prior art constructions, axial movement of the shackle has occurred without the knowledge of the user, with the dials being rotated to a new combination, completely unknown to the user.
By employing the construction provided in the present invention, unwanted axial movement or slippage of the shackle""s long leg is prevented. In the present invention, the spring force is constantly acting upon the rim of the sleeve/bowl which is engaged with the terminating end of the long leg of the shackle. As a result, unwanted axial movement of the shackle is prevented.
Whenever a user wishes to alter the combination of the lock, the user must exert an activation force on the long leg of the shackle in order to axially move the shackle against the spring force. Only by providing an activation force to the shackle is the shackle leg able to move axially downwardly.
Once the shackle leg has been moved downwardly, the indicia bearing wheels are forced to move, thereby allowing this use to change the combination to a new setting. Once completed, the activation force is removed and the spring force causes the sleeve/bowl and shackle to be returned to their original positions. In addition, the spring means and the sleeve/bowl continue to biasingly maintain the shackle in this raised position, providing assurance that the newly set combination cannot be altered or changed accidentally.
The invention accordingly comprises an article of manufacture possessing the features, properties, and the relation of elements which will be exemplified in the article hereinafter described and the scope of the invention will be indicated in the claims.